Dual motor torque monitoring

The present disclosure relates to electric vehicles (EVs). More particularly, the present disclosure relates to dual motor torque monitoring for EVs.

Embodiments of the present disclosure advantageously provide systems and methods for dual motor torque monitoring.

In certain embodiments, a method for dual motor torque monitoring includes determining torque errors for a first motor, determining torque errors for a second motor, determining combined torque errors for the first motor and the second motor, determining a torque fault based on the torque errors for the first motor, the torque errors for the second motor and the combined torque errors, and executing a predetermined function based on the torque fault. In certain embodiments, the predetermined function includes transmitting a torque fault notification message from a motor control unit processor to a vehicle control system processor.

Generally, electric vehicles (EVs) may be classified into different categories based on the architecture of the propulsion system. All-electric vehicles (AEVs), also known as full-electric vehicles (FEVs) or battery electric vehicles (BEVs), are propelled by AC motors that are connected to gearboxes that drive the wheels. The AC motors are powered by a DC battery pack that must be periodically recharged at a charging station. Hybrid electric vehicles (HEVs) and plug-in hybrid electric vehicles (PHEVs) are also propelled by AC motors that are powered by a DC battery pack, but additionally incorporate an internal combustion engine that drives a generator to recharge the DC battery pack. Some HEVs and PHEVs may also connect the internal combustion engine to a common gearbox or transmission to drive the wheels.

An electric drive unit (EDU) combines an AC motor, a gearbox, and a motor control unit (MCU) into a single mechanical package. The MCU includes, inter alia, a processor, a controller, etc., and an inverter that converts DC power provided by the battery pack to AC power provided to the AC motor. The inverter controls the speed and torque of the AC motor by adjusting the AC motor voltage frequency (proportional to speed) and the AC motor current (proportional to torque). Many EVs use Permanent-Magnet Synchronous Motors (PMSMs), which are powered by continuous sinusoidal AC current and use permanent magnets in the rotor (whose N-S axes may be axially aligned with the output shaft) and electromagnets in the stator. Other EVs use asynchronous AC induction motors, which use electromagnets in the both the rotor and the stator. Synchronous reluctance motors (SynRM) and internal permanent-magnet IPM SynRMs may also be used.

A single-motor EV provides either front-wheel drive or rear-wheel drive, and has a front EDU connected to the front wheels or a rear EDU connected to the rear wheels, respectively. The EDU has a single AC motor, a single gearbox connected to a limited-slip differential, and a single MCU. The differential is connected to each front wheel or each rear wheel.

A dual-motor EV provides all-wheel drive, and has a front EDU connected to the front wheels and a rear EDU connected to the rear wheels. Each EDU has a single AC motor, a single gearbox connected to a limited-slip differential, and a single MCU. The front EDU differential is connected to each front wheel, and the rear EDU differential is connected to each rear wheel.

A quad-motor EV also provides all-wheel drive, and has a front dual motor EDU connected to the front wheels (front axle), and a rear dual motor EDU connected to the rear wheels (rear axle). In other words, a quad-motor EV has two motors per axle. Each dual motor EDU has two AC motors, two gearboxes, and two MCUs or a single MCU with two processors, two inverters, etc. Each AC motor is connected to a gearbox, and each gearbox is connected to one wheel.

In a dual motor EDU, each processor independently controls the speed and torque of one motor based on commands received from the EV control system.

Accordingly, because each processor: (i) must independently determine whether the estimated motor torque complies with an axle torque limit, (ii) has no visibility over the other processor or the torque produced by the other motor, and (iii) must assume a worst-case scenario with respect to the torque being produced by the other motor, the axle torque limit is divided in half to generate a motor torque limit for each motor. Unfortunately, the reduction of the axle torque limit by 50% may generate false alarms (false torque faults), i.e., conditions in which the axle torque limit is actually not exceeded because the combination of estimated motor torque from both motors is less than the axle torque limit.

For example, if the estimated motor torque from one motor was 10% above the motor torque limit and the estimated motor torque from the other motor was 50% below the motor torque limit, then a false alarm would be generated even though the estimated motor torque from both motors is 20% below the axle torque limit.

Embodiments of the present disclosure advantageously provide a system and method for dual motor torque monitoring that provides a high level of motor torque integrity at higher speeds (such as 2,000 rpm and above) as well as lower speeds (such as 1,000 rpm). Embodiments described herein further provide visibility and control over both processors and the torque produced by the both motors for recovery and other purposes, and set the motor torque limit for each motor to the axle torque limit, which significantly decreases the probability of false alarms (false torque faults). Accordingly, embodiments of the present disclosure advantageously provide, inter alia, broader operation coverage, and enhanced redundancy, etc.

depicts a diagram of electric vehicle, in accordance with embodiments of the present disclosure.

Electric vehicleincludes, inter alia, a frame and body, an electrical power storage and distribution system, a propulsion system, a suspension system, a steering system, auxiliary and accessory systems (such as thermal management, lighting, wireless communications, navigation, etc.), etc.

Generally, bodymay be directly or indirectly mounted to a frame (i.e., body-on-frame construction), or bodymay be formed integrally with a frame (i.e., unibody construction). Bodyincludes, inter alia, front end, front light bar, front turn lights, stadium light ring, headlights, charging portwith charging port coverconcealing charging connector socket, driver/passenger compartment or cabin, bed, rear endwith rear tail lights, a rear light bar, etc. Electric vehiclemay be a pickup truck, a sport utility vehicle (SUV) in which bedis replaced by an extension of cabin, or a sedan in which bedis replaced by a trunk. In certain embodiments, electric vehicle may be an electric delivery vehicle, an electric cargo van, etc.

The propulsion system may include, inter alia, one or more ECUs, one or more EDUs, wheels, etc. The electrical power storage and distribution system may include, inter alia, one or more ECUs, a battery pack including one or more battery modules, a vehicle charging subsystem including charging port, high voltage (HV) cables, etc.

presents a block diagram of example components of electric vehicle, in accordance with embodiments of the present disclosure.

Generally, electric vehicleincludes control systemthat is configured to perform the functions necessary to operate electric vehicle. In certain embodiments, control systemincludes a number of ECUscoupled to ECU bus(also known as a controller area network or CAN). Each ECUperforms a particular set of functions, and includes, inter alia, microprocessorcoupled to memoryand ECU bus interface (I/F).

Microprocessormay be a microcontroller unit, a microprocessing unit, a central processing unit (CPU), a programmable logic device (PLD), a complex PLD, a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), etc. Memorymay include non-volatile and/or volatile memory, such as read only memory (ROM), random access memory (RAM), static RAM (SRAM), dynamic RAM (DRAM), flash memory, etc.

In certain embodiments, control systemmay include a number of system-on-chips (SoCs). Each SoC may include a number of multi-core processors coupled to a high-speed interconnect and on-chip memory that provide more robust functionality and performance than a single ECU. Accordingly, each SoC may combine the functionality provided by several ECUs.

Control systemmay be coupled to sensors (such as cameras, radar sensors, ultrasonic sensors, etc.), actuators (such as electric, hydraulic, pneumatic, etc.), input/output (I/O) devices, as well as other components within the propulsion system, the electrical power storage and distribution system, the suspension system, the steering system, the auxiliary and accessory systems, etc., such as dual motor EDU, battery pack, etc.

Control systemmay include central gateway module (CGM) ECU, which provides a central communications hub for electric vehicle. CGM ECUincludes (or is coupled to) I/O interfaces (I/Fs)to receive data from, and send commands to, various vehicle components, such as sensors, actuators, input devices, output devices, etc. CGM ECUalso includes (or is coupled to) network interfaces (I/Fs)to provide network connectivity through ECU bus ports, local interconnect network (LIN) ports, Ethernet ports, etc.

CGM ECUmay route messages (including commands, data, etc.) over ECU busfrom one ECUto another ECU, or from one ECUto multiple ECUs(such as broadcast messages, etc.). In one example, CGM ECUmay receive a message from a source ECU, process the message to determine, inter alia, the destination ECU, and then transmit the message to the destination ECU. In another example, CGM ECUmay simply arbitrate ECU busto allow the source ECUto send a message directly to the destination ECU. For example, VDM ECUmay send a message to motor control unit (XCC) ECUthat includes the torque commands for dual motor EDU, etc.

CGM ECUmay receive data from a sensor, an I/O device, a vehicle component, etc., and then send a message containing the data to the appropriate ECUover ECU bus. Similarly, CGM ECUmay receive a message containing a command or data from a source ECU, and then send the command or the data to the appropriate actuator, I/O device, vehicle component, etc. Additionally, CGM ECUmay manage the vehicle mode (such as road driving mode, off-roading mode, tow mode, camping mode, parked mode, etc.), and may control certain vehicle components related to transitioning from one vehicle mode to another vehicle mode.

Control systemmay include telematics control module (TCM) ECUwhich provides a wireless communications hub for electric vehicle. TCM ECUmay include (or may be coupled to) Bluetooth (or Bluetooth Low Energy) transceiver, WiFi transceiver, GPS receiver, etc.

Control systemmay include battery management system (BMS) ECUto manage the charging of battery pack, as well as to perform other related tasks.

In certain embodiments, one or more ECUsmay include the necessary interfaces to be coupled directly to particular sensors, actuators, I/O devices, and other vehicle system components. For example, BMS ECUmay be coupled directly to battery pack, motor control unit (XCC) ECUmay be coupled directly to one or more EDUs, etc. Additionally, components may also be coupled directly to one another. For example, battery packmay be directly coupled to one or more EDUs, etc.

In certain embodiments, dual motor EDUmay include, inter alia, MCUthat controls a dual motor drive unit configuration including motor.coupled to gearbox.(which is coupled to one wheel), and motor.coupled to gearbox.(which is coupled to one wheel). MCUmay include, inter alia, supervisory processor, processor., processor., non-volatile and/or volatile memory (such as ROM, RAM, SRAM, DRAM, flash memory, etc.), a communications interface for XCC ECU, etc. Supervisory processor, processor., and processor.may be microcontroller units, microprocessing units, CPUs, PLDs, CPLDs, FPGAs, ASICs, etc.

At least a portion of the memory may be accessible to supervisory processor, processor., and processor.as global RAM, in which variables with global scope may be stored, as well as other data. In certain embodiments, supervisory processor, processor., and processor.may read from and write to all of the global RAM. In other embodiments, supervisory processorand processor.may read from and write to a first section of global RAM, while supervisory processorand processor.may read from and write to a second (different) section of global RAM.

In certain embodiments, supervisory processorand processors.,.may be multiple integrated circuit devices working in cooperation to accomplish the requisite functionality. In other embodiments, supervisory processorand processors.,.may be configured as multiple processors within a single integrated device, such as a SoC, etc. In other embodiments, supervisory processorand processors.,.may be configured as a single processor with multiple processing cores (i.e., a multi-core processor), with each processing core providing respective functionality.

Processor.is coupled to inverter., converter., and motor., and processor.is coupled to inverter., converter., and motor.. Inverter.and converter.are coupled to motor.and battery pack, while inverter.and converter.are coupled to motor.and battery pack. In certain embodiments, the functionality provided by inverter.and converter.may be combined into a single component, such as inverter.. Similarly, the functionality provided by inverter.and converter.may be combined into a single component, such as inverter..

Supervisory processorgenerally monitors and controls the operation of processors.,., and provides commands, parameters, and data to, and receives data from, processors.,.as well as XCC EDU. More particularly, supervisory processormay be configured to perform dual motor torque monitoring for motors.,.. Processor.generally controls the operation of inverter., converter., and motor., and receives commands, parameters, and data from, and provides data to, supervisory processor. Similarly, processor.generally controls the operation of inverter., converter., and motor., and receives commands, parameters, and data from, and provides data to, supervisory processorfor transmission to XCC ECU.

XCC ECUmay be coupled directly to supervisory processorvia a communication signal cable, BMS ECUmay be coupled directly to battery packvia a communication signal cable, and battery packmay be coupled directly to inverterand convertervia one or more HV cables.

In certain embodiments, control systemmay also include, inter alia, autonomy control module (ACM) ECU, autonomous safety module (ASM) ECU, body control module (BCM) ECU, battery power isolation (BPI) ECU, balancing voltage temperature (BVT) ECU, door control module (DCM) ECU, driver monitoring system (DMS) ECU, near-field communication (NFC) ECU, rear zone control (RZC) ECU, seat control module (SCM) ECU, thermal management module (TMM) ECU, vehicle access system (VAS) ECU, winch control module (WCM) ECU, experience management module (XMM) ECU, etc.

presents a block diagram illustrating dual motor torque monitoring processing architecture, in accordance with embodiments of the present disclosure.

Generally, the functionality associated with dual motor torque monitoring may be apportioned to one or more processing modules, such as software modules that are executed by supervisory processor. In certain embodiments, the processing modules may include one or more PLDs, complex PLDs, FPGAs, ASICs, custom circuitry, etc., that cooperate with software modules executed by supervisory processorto perform dual motor torque monitoring.

In certain embodiments, dual motor torque monitoring processing architecturemay include, inter alia, TM modulefor motor(motor.), TM modulefor motor(motor.), TM modulefor motorand motor(motor.and motor.), and TM modulefor fault triggering. Datamay include, inter alia, torque commands and parameters, such as model torque estimates for motorsand, loss torque estimates for motorsand, torque commands for motorsand, speeds for motorsand, minimum speed limits for motorsand, etc. Datamay be provided to TM module, TM module, and TM moduleat a certain update rate, such as 1 Hz, 2 Hz, etc. Generally, datamay be provided by supervisory processor, processor., processor., control system(such as XCC ECU, etc.), etc.

Supervisory processormay be configured to periodically perform dual motor torque monitoring for motors.,., such as every 1 second (1 Hz), every 0.5 seconds (2 Hz), every 0.2 seconds (5 Hz), every 0.1 seconds (10 Hz), etc. Datamay be provided to supervisory processorat the same rate (1 Hz, 2 Hz, etc.) in order to support dual motor torque monitoring for motors.,..

Generally, TM module, TM module, TM module, and TM modulemay be provided as separate processing modules (such as separate software modules), as subprocesses within a single processing module (such as subroutines within a single software module), etc. Other processing architectures are also supported.

present block diagrams,, respectively, illustrating exemplary functionality for TM modulefor motor, in accordance with embodiments of the present disclosure.

Generally, TM modulegenerates a model-based torque error for motorand a loss-based torque error for motorby comparing the model-based torque estimate for motor, the torque command for motor, and the loss-based torque estimate for motor.

More particularly,presents a first portion of the functionality for TM module, whilepresents a second portion of the functionality for TM module. The first portion of the functionality for TM modulegenerates several intermediate results for input to the second portion of the functionality for TM module.

As depicted in, TM modulereceives certain data from data, including, inter alia, model torque estimatefor motor, torque commandfor motor, and loss torque estimatefor motor. TM moduleprocesses these data, and outputs certain results to the second portion of the functionality for TM module, including model torque estimate errorfor motor, model-loss torque estimate differencefor motor, and loss torque estimate errorfor motor.

In certain embodiments, subtraction blockmay receive model torque estimateand torque commandfrom data, subtraction blockmay receive model torque estimateand loss torque estimatefrom data, and subtraction blockmay receive loss torque estimateand torque commandfrom data.

Subtraction blockreceives model torque estimateand torque command, subtracts torque commandfrom model torque estimate, and outputs model torque estimate errorfor motor. Subtraction blockreceives model torque estimateand loss torque estimate, subtracts loss torque estimatefrom model torque estimate, and outputs model-loss torque estimate differencefor motor. Subtraction blockreceives loss torque estimateand torque command, subtracts torque commandfrom loss torque estimate, and outputs loss torque estimate errorfor motor.

In other embodiments, respective digital filters may be applied to model torque estimate, torque command, and loss torque estimateas new dataarrive over time. For example, digital filtermay receive model torque estimateand output filtered model torque estimate., digital filtermay receive torque commandand output filtered torque command., and digital filtermay receive loss torque estimateand output filtered loss torque estimate.. Digital filters,,may be 1order digital filters, 2order digital filters, etc.

Subtraction blockreceives filtered model torque estimate.and filtered torque command., subtracts filtered torque command.from filtered model torque estimate., and outputs model torque estimate errorfor motor. Subtraction blockreceives filtered model torque estimate.and filtered loss torque estimate., subtracts filtered loss torque estimate.from filtered model torque estimate., and outputs model-loss torque estimate differencefor motor. Subtraction blockreceives filtered loss torque estimate.and filtered torque command., subtracts filtered torque command.from filtered loss torque estimate., and outputs loss torque estimate errorfor motor.

As depicted in, TM modulealso receives torque commandfor motor, motor speedfor motor, and motor speedfor motorfrom data. TM moduleprocesses the data received from dataas well as model torque estimate error, model-loss torque estimate difference, loss torque estimate error(described above), and outputs certain results to TM module, including model torque errorfor motor, and loss torque errorfor motor.

TM modulegenerates model torque errorbased on model torque estimate error(which is based on torque commandand model torque estimate) and model torque limitfor motor.

Advantageously, model torque limitfor motoris equal to the axle torque limit, which is twice the torque limit of each motor in the conventional method discussed above. This expands motor torque integrity all the way to half the speed of the conventional method, such as from 2,000 rpm (conventional method) to 1,000 rpm (certain embodiments of the present disclosure). Additionally, the use of the axle torque limit for motormay significantly reduce the probability of false torque triggering for model-based torque limits.